Identifying and characterizing the function of the numerous proteins that are required for normal visual function is an important goal in biomedical research. We describe a mutant mouse model whose phenotype mimics a human disease called congenital stationary night blindness (CSNB). The mouse mutation has been named nob because its electroretinogram has no b-wave. Our preliminary studies have localized the nob gene to the X-chromosome, in a region syntenic to that in humans that contains the genes responsible for CSNB1, CSNB2 and CSNB4, and two forms of retinitis pigmentosa (RP2 and RP3). The specific aims are: (1) localize the nob gene to a specific region on the X-chromosome, (2) identify the mouse nob gene by positional cloning and (3) determine if mutations in the human homologue of nob are responsible for eye disease. We hypothesize that the isolation and characterization of the mutation in this gene responsible for disrupting communication between the outer and inner retina will provide insight into the complex mechanism of synaptic transmission in the outer retina. Further, this mutant mouse will provide a model system in which to study gene therapy in the retina. The ultimate goal of these studies is to gain a more complete understanding of the mutation and its role in disrupting normal visual function, so that more targeted therapies can be devised to either cure or treat associated eye diseases.